Update README.md

README.md

@@ -13,6 +13,12 @@ If not done yet, install git and virtualenv for python 3:
 sudo apt install git python3-venv
 ```
 
+Optionally, to enable suggesting alternatives on typos, also install these packages (they are required by `python-Levenshtein`):
+```bash
+# If not installed yet.
+sudo apt install gcc libpython3-dev
+```
+
 Then clone the repository:
 ```bash
 cd ~  # Or another directory of your choice.